Effect of swift heavy ion irradiation in FePt system

The present study reports the effects of swift heavy ion irradiation in FePt system in different forms viz., uniform alloy film, multilayer, and nano-particles in non-magnetic medium. The FePt alloy film, Fe/Pt multilayer and FePt nano-particles in silver matrix with partial L10 ordering, are prepared by ion beam sputtering method and subsequent vacuum annealing at 450 °C for 1 h. These samples are irradiated with swift heavy ions in order to study structural changes induced due to electronic energy loss by the bombarding ions. X-ray diffraction and magneto-optical Kerr effect are used for the characterisation of the unirradiated and irradiated films. It is observed that irradiation results in partial destruction of L10 ordering. Irradiation effects are more pronounced in the case of nano-particles and multilayers as compared to that of continuous alloy film. The results are discussed using thermal spike model.